Film forming device

Abstract

To provide a film forming device capable of preventing a defective pattern resulting from crystallization of a metal ion sticking to the surface of a patterning mask by suppressing the metal ion present in a plating solution from crystallizing.SOLUTION: A film forming device 1 comprises an anode 11, an electrolyte membrane 13 disposed between the anode 11 and a substrate, i. e., a cathode, a mounting table 15 disposed to face the electrolyte membrane 13, for the substrate to be mounted thereon, a liquid storage chamber 14 comprising an opening 141 opening to the side of the mounting table 15 and closed by the electrolyte membrane 13 to house the anode 11 and a plating liquid S, a storage chamber moving unit 22 moving the liquid storage chamber 14 closer to or away from the mounting table 15, a patterning mask 12 disposed below the electrolyte membrane 13 and attached to the liquid storage chamber 14 together with the electrolyte membrane 13, and a cleaning container 17 detachably attached to the mounting table 15, for the patterning mask 12 to be immersed therein.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a film forming apparatus, and particularly to a film forming apparatus suitable for the solid phase electrolysis method.

Background Art

[0002] The solid phase electrolysis method is a method of forming a metal film derived from metal ions contained in an electrolyte membrane on the surface of a substrate by applying a voltage between the substrate, which is an anode and a cathode, while pressing the substrate with the electrolyte membrane in contact with a plating solution containing metal ions. As a film forming apparatus suitable for the solid phase electrolysis method, there is known one including a liquid storage chamber that houses an anode and a plating solution and has an opening on the substrate side blocked by an electrolyte membrane, a mounting table that is arranged to face the liquid storage chamber and on which the substrate is mounted, and a power supply unit that applies a voltage between the anode and the substrate.

[0003] Recently, a film forming apparatus has been developed that forms a wiring layer by forming a metal film in an area corresponding to a wiring pattern using a patterning mask. However, in a film forming apparatus using a patterning mask, if left for a long time after the metal film is formed, metal ions in the plating solution adhering to the patterning mask crystallize on the surface of the patterning mask, leading to wiring pattern defects such as non-deposition and pattern bleeding. For example, when the plating solution is a solution containing copper sulfate, if left for a long time after film formation, due to the volatilization of moisture, the plating solution adhering to the surface of the patterning mask becomes concentrated. Then, when the solubility is exceeded, copper sulfate crystallizes on the surface of the patterning mask. The crystallized copper sulfate becomes a foreign substance, and a problem of non-deposition of metal occurs at that location. Further, when pressing the patterning mask against the substrate, the crystallized copper sulfate bites into the patterning mask, thereby causing the patterning mask to float and reducing the sealing property, leading to the occurrence of pattern bleeding.

[0004] In order to solve such problems, for example, as described in Patent Document 1 below, a method of cleaning the patterning mask using a water washing tank has been studied.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-185122 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, there was a problem in that the washing tank described in Patent Document 1 above could not be directly applied to the film deposition apparatus.

[0007] The present invention was made to solve these technical problems, and aims to provide a film deposition apparatus that can suppress the crystallization of metal ions in the plating solution attached to the surface of a patterning mask, thereby preventing pattern defects caused by the crystallization of metal ions. [Means for solving the problem]

[0008] The film-forming apparatus according to the present invention is characterized by comprising: an anode; an electrolyte membrane disposed between the anode and a substrate which is the cathode; a mounting table disposed opposite the electrolyte membrane on which the substrate is placed; a liquid storage chamber for storing the anode and a plating solution, with an opening that opens toward the mounting table and is closed by the electrolyte membrane; a storage chamber moving unit for moving the liquid storage chamber toward or away from the mounting table; a patterning mask disposed below the electrolyte membrane and attached to the liquid storage chamber together with the electrolyte membrane; and a cleaning container that is detachably disposed relative to the mounting table and into which the patterning mask can be immersed.

[0009] The film deposition apparatus according to the present invention is equipped with a cleaning container that is detachably positioned on the mounting table and into which a patterning mask can be immersed. For example, after deposition on the substrate, the cleaning container can be placed on the mounting surface, and the patterning mask attached to the liquid storage chamber can be immersed in the solution in the cleaning container to clean the plating solution adhering to the surface of the patterning mask. As a result, the crystallization of metal ions in the plating solution adhering to the surface of the patterning mask can be suppressed, and pattern defects caused by the crystallization of metal ions can be prevented. Furthermore, since the cleaning container is detachably positioned on the mounting table, the cleaning container can be removed from the mounting surface of the mounting table during deposition on the substrate, thereby preventing interference with film deposition. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress the crystallization of metal ions in the plating solution that adhere to the surface of the patterning mask, thereby preventing pattern defects caused by the crystallization of metal ions. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing a film deposition apparatus according to an embodiment. [Figure 2] This is a schematic cross-sectional view showing a patterning mask being immersed in a washing container. [Figure 3] This is a schematic cross-sectional view showing a modified example of a washing container. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the film deposition apparatus according to the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. In the following description, "up" refers to the direction away from the mounting table which is positioned opposite the liquid containment chamber, and "down" refers to the direction approaching the mounting table.

[0013] The substrate (not shown) described in this embodiment is a component for manufacturing a wiring board, and for example, comprises an insulating substrate and a metal seed layer formed on the surface of the insulating substrate. The wiring board comprises the insulating substrate and a wiring layer with a predetermined wiring pattern provided on the surface of the insulating substrate. The wiring layer is composed of the metal seed layer and a metal layer further formed on the surface of the metal seed layer. This metal layer consists of a metal film formed using the film deposition apparatus of this embodiment.

[0014] The insulating substrate is not particularly limited as long as it has insulating properties, but it is preferable to use, for example, a substrate made of glass epoxy resin, a substrate made of fired glass epoxy resin, a flexible film-like substrate such as polyimide resin, or a substrate made of glass.

[0015] The metal seed layer is, for example, at least one selected from the group consisting of silver, copper, gold, nickel, palladium, and platinum.

[0016] Figure 1 is a schematic cross-sectional view showing a film deposition apparatus according to an embodiment. The film deposition apparatus 1 of this embodiment is a plating apparatus that forms the metal layer by depositing a metal film in an area corresponding to a wiring pattern using a solid-phase electrodeposition method. The film deposition apparatus 1 comprises a metal anode 11, an electrolyte membrane 13 disposed between the anode 11 and a substrate as a cathode, a liquid storage chamber 14 that contains the anode 11 and the plating solution S, a mounting table 15 disposed below the liquid storage chamber 14 on which the substrate is placed, and a power supply unit 16 that applies a voltage between the anode 11 and the substrate.

[0017] The anode 11 may be plate-shaped, mesh-shaped, porous, or a metal ball, and is embedded in the top plate portion 142 of the liquid storage chamber 14, facing the electrolyte membrane 13, so as to be able to contact the plating solution S filled in the liquid storage chamber 14. The anode 11 is electrically connected to the positive electrode of the power supply unit 16 via a wire or the like. This anode 11 may be a soluble anode made of the same material as the metal layer (e.g., copper), or an anode made of a material insoluble in the plating solution S (e.g., titanium).

[0018] The liquid storage chamber 14 is made of a material insoluble in the plating solution S, and is formed to have a space for storing the plating solution S therein. The liquid storage chamber 14 has an opening 141 that opens downward (i.e., on the side of the mounting table 15). The opening 141 is blocked by the electrolyte membrane 13.

[0019] Also, the liquid storage chamber 14 is provided with a supply port 14a through which the plating solution S is supplied and a discharge port 14b through which the plating solution S is discharged. The supply port 14a and the discharge port 14b are formed in the side wall portion 143 of the liquid storage chamber 14 and are connected to the tank 19 and the pump 20 via pipes. Then, the plating solution S sent out from the tank 19 by the pump 20 flows into the interior of the liquid storage chamber 14 from the supply port 14a, is discharged from the discharge port 14b, and returns to the tank 19. Further, a pressure regulating valve 21 is provided on the downstream side of the discharge port 14b, and the plating solution S in the liquid storage chamber 14 can be pressurized at a predetermined pressure by the pressure regulating valve 21 and the pump 20.

[0020] The electrolyte membrane 13 is a so-called solid electrolyte membrane and is made of a porous membrane or a porous resin membrane having a certain flexibility. The electrolyte membrane 13 is disposed below the liquid storage chamber 14 so as to face the anode 11 and blocks the opening 141. The electrolyte membrane 13 impregnates (contains) metal ions contained in the plating solution S therein by contacting the plating solution S stored in the liquid storage chamber 14. Then, when a voltage is applied in a state of being in close contact with the base material, the electrolyte membrane 13 deposits a metal derived from the metal ions on the surface of the base material (more specifically, the surface of the metal seed layer), thereby forming the metal layer.

[0021] Examples of the material of the electrolyte membrane 13 include fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont, hydrocarbon-based resins, polyamic acid resins, and resins having an ion exchange function such as Selemion (CMV, CMD, CMF series) manufactured by Asahi Glass Co., Ltd. The thickness of the electrolyte membrane 13 is, for example, 5 to 200 μm.

[0022] Below the electrolyte membrane 13, a patterning mask 12 is disposed. The patterning mask 12 is a plating mask for forming a predetermined wiring pattern on the surface of the substrate, and is in close contact with the lower surface of the electrolyte membrane 13. Although not shown, the electrolyte membrane 13 and the patterning mask 12 are detachably attached to the bottom of the liquid storage chamber 14 by a member or jig that supports their peripheral portions.

[0023] The plating solution S is a solution containing the metal of the metal film to be formed (i.e., the metal of the above metal layer) in an ionic state, and examples of the metal include copper, nickel, silver, or tin. The plating solution S is an aqueous solution in which these metals are dissolved (ionized) with an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, or pyrophosphoric acid. For example, when the metal is nickel, examples of the plating solution S include aqueous solutions of nickel nitrate, nickel phosphate, nickel succinate, nickel sulfate, nickel pyrophosphate, or nickel sulfamate. When the metal is copper, examples of the plating solution S include aqueous solutions containing copper sulfate, copper pyrophosphate, etc. In the present embodiment, the plating solution S is an aqueous solution containing copper sulfate.

[0024] The mounting table 15 is made of a conductive material and is disposed below the liquid storage chamber 14 so that the substrate to be mounted faces the electrolyte membrane 13. The mounting table 15 is electrically connected to the negative electrode of the power supply unit 16. The upper surface of the mounting table 15 facing the liquid storage chamber 14 forms a mounting surface (not shown) for mounting the substrate. In a state of being mounted on the mounting surface, the metal seed layer of the substrate is electrically connected to the mounting table 15 via a conductive member not shown.

[0025] Furthermore, the film deposition apparatus 1 is equipped with a storage chamber moving unit 22 positioned above the liquid storage chamber 14, which moves the liquid storage chamber 14 closer to or further away from the mounting base 15. The storage chamber moving unit 22 is composed of, for example, a hydraulic or pneumatic cylinder, an electric actuator, a linear guide, and a motor. By driving the storage chamber moving unit 22, the liquid storage chamber 14 can be moved closer to the mounting base 15 so that the electrolyte membrane 13, which is attached below the liquid storage chamber 14, can come into contact with the substrate placed on the mounting surface. Also, by driving the storage chamber moving unit 22, the liquid storage chamber 14 can be moved away from the mounting base 15 so that the electrolyte membrane 13 is separated from the substrate.

[0026] Furthermore, the film deposition apparatus 1 of this embodiment is equipped with a cleaning container 17 that is detachably positioned on the mounting table 15 and into which the patterning mask 12 can be immersed. The cleaning container 17 is a water tank that opens upward (i.e., towards the liquid storage chamber 14). The opening of the cleaning container 17 is formed to be slightly larger than the lower surface of the patterning mask 12 so that the patterning mask 12 attached to the bottom of the liquid storage chamber 14 can be smoothly immersed.

[0027] As shown in Figure 1, the washing container 17 is equipped with, for example, wheels and is guided by rails 24 stretched between a pair of bases 18, allowing it to move between a washing position on the mounting surface of the mounting platform 15 and a retracted position away from the mounting surface. Position regulating members 23 are provided at both ends of the rails 24 to restrict the range of movement of the mounting platform 15. The washing container 17 is made of, for example, a resin material.

[0028] The following describes immersing the patterning mask 12 in the washing container 17, based on Figure 2. In Figure 2, the solution contained in the washing container 17 (in this case, pure water W) is shown in gray to make the immersion state of the patterning mask 12 clearer. Pure water W is used to wash the patterning mask 12, and preferably, pure water W with a conductivity of 3 μS / cm or less at room temperature is used.

[0029] The appropriate amount of pure water W to be contained in the washing container 17 is such that it does not overflow when the patterning mask 12 is completely immersed, and the amount is such that when the copper sulfate in the patterning mask 12 dissolves in the pure water W, it falls below the saturation solubility of copper sulfate.

[0030] The patterning mask 12 is cleaned by lowering the liquid storage chamber 14 using the storage chamber movement unit 22, and immersing the patterning mask 12 in the pure water W of the cleaning container 17. At this time, it is necessary to leave a certain gap (for example, about 1 mm) so that the lower surface of the patterning mask 12 does not touch the bottom surface of the cleaning container 17. This is because if the lower surface of the patterning mask 12 touches the bottom surface of the cleaning container 17, the copper sulfate crystallized on the lower surface of the patterning mask 12 may become embedded in the patterning mask 12 due to the pressure. Once copper sulfate becomes embedded, it is difficult to remove, and in some cases, the patterning mask 12 may become unusable.

[0031] Furthermore, the patterning mask 12 is cleaned within 10 minutes after film formation, for example, when no further film formation is performed after film formation on the substrate. In addition, when immersing the patterning mask 12 in the pure water W of the cleaning container 17, the liquid storage chamber 14 is moved up and down using the storage chamber movement unit 22 to agitate the patterning mask 12, thereby promoting the dissolution of crystallized copper sulfate. Moreover, the dissolution of copper sulfate can be further promoted by setting the temperature of the pure water W to room temperature to 40°C.

[0032] As shown in Figure 2, in this embodiment, the electrolyte membrane 13, which is in close contact with the patterning mask 12, is also immersed in the pure water W of the washing container 17. However, it is sufficient to immerse only the patterning mask 12 in the pure water W. Nevertheless, immersing both the patterning mask 12 and the electrolyte membrane 13 in the pure water W can be expected to suppress the drying of the surface of the electrolyte membrane 13.

[0033] In the film deposition apparatus 1 of this embodiment, a cleaning container 17 is provided that is detachably positioned on the mounting table 15 and into which the patterning mask 12 can be immersed. For example, after film deposition, the cleaning container 17 can be moved to a cleaning position (i.e., a position on the mounting surface of the mounting table 15), and the patterning mask 12 attached to the liquid storage chamber 14 can be immersed in the pure water W in the cleaning container 17 to clean the plating solution S adhering to the surface of the patterning mask 12. Therefore, the crystallization of copper sulfate in the plating solution S adhering to the surface of the patterning mask 12 can be suppressed, and pattern defects caused by copper sulfate crystallization can be prevented. Furthermore, since the cleaning container 17 is detachably positioned on the mounting table 15, when deposition of the substrate, the cleaning container 17 can be removed from the mounting surface of the mounting table 15 and moved to a retracted position to prevent interference with film deposition. As a result, even when the patterning mask 12 is left for a long time during repeated continuous film deposition, the quality of the film deposition can be ensured without the occurrence of pattern defects.

[0034] [Examples and Comparative Examples] Furthermore, in order to verify the effects of the invention, the inventors of the present invention evaluated the film deposition apparatus 1 equipped with a cleaning container 17 (Example) and a film deposition apparatus without a cleaning container (Comparative Example) as follows. In both the Example and the Comparative Example, the first film deposition was performed under conditions of a temperature of 40°C and a film deposition rate of 1.5 μm / min, after which the substrate was replaced and the second film deposition was performed under the same conditions.

[0035] In this example, after the first film deposition and before replacing the substrate, the patterning mask 12 was immersed in pure water W in the washing container 17 for cleaning. Then, a second film deposition was performed. The condition of the pattern on the substrate after the second deposition was checked. As a result, there was no pattern bleeding.

[0036] On the other hand, in the comparative example, after the first film deposition and after replacing the substrate, the patterning mask 12 was left for 60 minutes, and then the second film deposition was performed. The condition of the pattern on the substrate after the second film deposition was checked. As a result, copper sulfate crystals were confirmed on the surface of the patterning mask 12, and pattern bleeding was also confirmed.

[0037] The results above demonstrate that the film deposition apparatus 1 of this embodiment can suppress the crystallization of metal ions (copper sulfate) in the plating solution that adhere to the surface of the patterning mask, thereby preventing pattern defects caused by the crystallization of metal ions.

[0038] [Differentiation] Various modifications of the washing container 17 according to this embodiment are also conceivable.

[0039] For example, in the modified example shown in Figure 3(a), a sheet 25 of a certain thickness is placed on the bottom surface of the cleaning container 17A to prevent the patterning mask 12 from touching the bottom surface of the cleaning container 17A. The sheet 25 is made of a material that is resistant to the plating solution S and is softer than the material of the patterning mask 12. Furthermore, it is preferable that the sheet 25 has a sawtooth cross-section so that even if it comes into contact with the lower surface of the patterning mask 12, it does not hinder the cleaning of the lower surface of the patterning mask 12. Moreover, by making the cross-section of the sheet 25 sawtooth, it is possible to suppress the crystallized copper sulfate from penetrating into the patterning mask 12 even when the patterning mask 12 is pressed.

[0040] Furthermore, in the modified example shown in Figure 3(b), a stepped portion 171 is provided on the bottom edge of the cleaning container 17B. The height of the stepped portion 171 is, for example, about 1 mm from the bottom surface of the cleaning container 17B. This stepped portion 171 may be integrally formed from the same material as the cleaning container 17B, or it may be formed separately from the cleaning container 17B and fixed to the cleaning container 17B by adhesive or the like. In addition, it is preferable that the stepped portion 171 be provided in areas where there is no wiring pattern so as not to interfere with the formation of the wiring pattern.

[0041] By providing the stepped portion 171 in this way, when the patterning mask 12 is immersed in the pure water W of the washing container 17B, the immersion depth of the patterning mask 12 can be restricted by the lower surface of the patterning mask 12 coming into contact with the upper surface of the stepped portion 171. This makes it easy to secure a certain gap between the lower surface of the patterning mask 12 and the bottom surface of the washing container 17B.

[0042] Furthermore, in the modified version shown in Figure 3(c), an ultrasonic generator 26 is provided. In this modified version, instead of oscillating the liquid containment chamber 14 up and down, the ultrasonic generator 26 is inserted into the pure water W, and the copper sulfate formed on the surface of the patterning mask 12 is cleaned by applying vibration to the pure water W. In this case, in order to suppress the dissolution of metal ions (copper sulfate), the metal ultrasonic generator 26 is placed in the cleaning container 17C and immersed in the pure water W.

[0043] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims. [Explanation of symbols]

[0044] 1: Film deposition apparatus, 11: Anode, 12: Patterning mask, 13: Electrolyte membrane, 14: Liquid storage chamber, 14a: Supply port, 14b: Discharge port, 15: Mounting platform, 16: Power supply unit, 17, 17A, 17B, 17C: Washing container, 18: Base, 19: Tank, 20: Pump, 21: Pressure regulating valve, 22: Storage chamber movement unit, 23: Position regulating member, 24: Rail, 25: Sheet, 26: Ultrasonic generator, 141: Opening, 142: Top plate, 143: Side wall, 171: Stepped section

Claims

[Claim 1] Anode and, An electrolyte membrane is disposed between the anode and the cathode substrate, A mounting platform is positioned opposite the electrolyte membrane and on which the substrate is placed, The opening on the mounting table side is closed by the electrolyte membrane, and a liquid storage chamber for containing the anode and plating solution is formed. A storage chamber moving unit that moves the liquid storage chamber closer to or further away from the stand described above, A patterning mask is positioned below the electrolyte membrane and attached together with the electrolyte membrane to the liquid containment chamber, A washing container is provided which the patterning mask can be immersed in and which is detachably positioned on the mounting base, A film deposition apparatus characterized by comprising the following features.

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